Sacrificial yarns for use in ceramic matrix composites, methods of manufacture thereof and articles comprising the same

Abstract

Disclosed herein is a composite co-fiber comprising a plurality of ceramic tows; one or more sacrificial yarns; where the sacrificial yarns are operative to undergo dissolution, decomposition or melting upon being subjected to an elevated temperature; and wherein the sacrificial yarns leave open spaces in the co-fiber upon being subjected to decomposition, dissolution or melting.

What is claimed is: 
     
         1 . A composite co-fiber comprising:
 a plurality of ceramic tows;   one or more sacrificial yarns; where the sacrificial yarns are operative to undergo dissolution, decomposition or melting upon being subjected to an elevated temperature; and wherein the sacrificial yarns leave open spaces in the co-fiber upon being subjected to decomposition, dissolution or melting.   
     
     
         2 . The composite co-fiber of  claim 1 , wherein the ceramic tows comprise SiC, Al 2 O 3 , BN, B 4 C, Si 3 N 4 , MoSi 2 , SiO 2 , SiOC, SiNC, and/or SiONC. 
     
     
         3 . The composite co-fiber of  claim 1 , wherein the sacrificial yarns comprise metal fibers, ceramic fibers, polymeric fibers or a combination thereof. 
     
     
         4 . The composite co-fiber of  claim 3 , wherein the metal fibers and ceramic fibers melt or decompose at temperatures of less than 500° C. 
     
     
         5 . The composite co-fiber of  claim 3 , wherein the polymeric fibers comprise thermoplastic polymers, blend of thermoplastic polymers, thermosetting polymers, or blends of thermoplastic polymers with thermosetting polymers. 
     
     
         6 . The composite co-fiber of  claim 1 , wherein the sacrificial yarn is present in the composite co-fiber in an amount of greater than or equal to 20 wt %, based on a total weight of the composite co-fiber. 
     
     
         7 . The composite co-fiber of  claim 1 , wherein the sacrificial yarn is present in the composite co-fiber in an amount of greater than or equal to 35 wt %, based on a total weight of the composite co-fiber. 
     
     
         8 . The composite co-fiber of  claim 1 , wherein the sacrificial yarn is present in the composite co-fiber in an amount effective to create a percolating volume fraction. 
     
     
         9 . The composite co-fiber of  claim 1 , wherein the sacrificial yarn is present in a larger amount at an outer periphery of the composite co-fiber relative to the amount present in a center of the composite co-fiber. 
     
     
         10 . The composite co-fiber of  claim 1 , wherein the sacrificial yarn comprises a water soluble polymer. 
     
     
         11 . The composite co-fiber of  claim 1 , wherein the sacrificial yarn comprises polyvinyl alcohol, polyacrylamide, or a combination thereof. 
     
     
         12 . An article manufactured from the composite co-fiber of  claim 1 . 
     
     
         13 . The article of  claim 12 , wherein the article is a space filling insert. 
     
     
         14 . The article of  claim 13 , wherein the space filling insert is used in a turbine component. 
     
     
         15 . A method of manufacturing a ceramic matrix composite comprising:
 co-braiding a sacrificial yarn with a ceramic tow to form the composite co-fiber;   melting, dissolving or decomposing the sacrificial yarn to form a space in the composite co-fiber; and   infiltrating the space with a ceramic precursor to form a ceramic matrix.   
     
     
         16 . The method of  claim 15 , wherein the sacrificial yarn comprises thermoplastic polymers, blend of thermoplastic polymers, thermosetting polymers, or blends of thermoplastic polymers with thermosetting polymers. 
     
     
         17 . The method of  claim 15 , wherein the ceramic matrix comprises SiC. 
     
     
         18 . The method of  claim 17 , wherein the ceramic tow comprises SiC. 
     
     
         19 . The method of  claim 15 , further comprising reacting the ceramic precursor with itself to form the ceramic matrix. 
     
     
         20 . The method of  claim 15 , wherein the co-braiding is conducted to produce a space filling insert.